LM, RL, and JB have begun new work on this project as of July, 1995. Initial work involves the use of cultured mosquito cells freshly derived from species that do (Aedes aegypti, subgenus steomyeia) and do not (subgenus non-stegomyeia) support replication of dengue viruses in vivo. It is hoped that the cultured cells will exhibit the same specificity for the growth of dengue viruses as do the adult mosquitoes from which they are derived. If this proves to be the case, it is reasonable to assume that species specificity is based upon the expression of dengue-specific receptors on permissive cells that are not present on non-permissive cells. Attempts will then be made to isolate and identify such a receptor by "subtracting" sequences in a cDNA library derived from non-permissive cells from those in a cDNA library derived from permissive cells. Unique sequences could then be expressed in the non-permissive cell line. Expression of a dengue-specific receptor in this cell line render it susceptible to dengue virus infection and replication. Identification of cellular receptors for flaviviruses will help provide an understanding of the pathogenesis of diseases caused by these agents.